1. Field of the Invention
The present invention relates to shaft couplings. More particularly, the invention relates to a free-floating coupling for joining rotatable shafts which tolerates shaft misalignment.
2. Description of the Prior Art
Rotatable shafts are typically used in motor powered mechanical devices such as pumps and the like. These devices cooperate with a motor via a rotatable shaft which, when rotated along a fixed axis, rotates other machine parts. Because these shafts can only reach limited lengths, they are often connected to one another to form a longer, continuous rotatable shaft. Attempts have been made in the art to compensate for misalignment in rotatable shafts, however rotational vibrations in such shafts and couplings eventually result in an angular distortion and misalignment between the shafts. Shaft axes inevitably exert a lateral force which causes bearing to wear out. This leads to improper shaft rotation.
Various attempts have been made to compensate for misalignment between rotatable shafts. U.S. Pat. No. 268,807 discloses a coupling for shafts which includes a pair of end units with openings for the shafts and which are held onto the shafts via set screws. The end units have links that connect to a central unit via spherical ends on the links and transmits motion thereby. The pins may be spherical but they do not directly connect the end units with the central disk, rather they are connected via intermediate linkages. U.S. Pat. No. 4,591,350 discloses a compensator coupling which includes an intermediate sleeve with resilient bushings for engaging shaft ends. A shaft presses against a spherical ring, and compression springs are required. U.S. Pat. No. 1,862,355 discloses a flexible coupling which includes a bar that carries spherical engagement pins. A bar is bent at right angles to form ends which carry spherical arrangement pins. U.S. Pat. No. 1,188,113 shows a three disk arrangement where the disks are attached by bolts surrounded by springs. U.S. Pat. No. 2,181,888 shows a three disk arrangement where the disks are indirectly connected via links. U.S. Pat. No. 1,482,097 shows a flexible coupling whose end members are linked by a support disk via straight pins. U.S. Pat. No. 3,304,743 shows a coupling having hubs which are connected via an intermediate plate. Ball connectors are intended to pivot and slide in the bore, and a shaft is required. U.S. Pat. No. 1,365,957 shows a spring coupling. U.S. Pat. No. 1,814,836 shows a shaft coupling with tapered coupling pins. Each of the foregoing designs are ineffective for tolerating shaft misalignment.
It would be desirable to provide a free-floating coupling device for joining rotatable shafts which tolerates vibration induced shaft misalignment. The coupling device of the present invention solves this problem. Such a coupling allows for flexibility at the joining point while tolerating misalignment in the rotatable shafts.